1. Field of the Invention
The present invention relates to a magnetic signal reproducing apparatus and, a magnetic signal reproducing method, for reproducing magnetic signals recorded in a magnetic tape by a magneto-resistance effect type magnetic head.
2. Description of the Related Art
A magneto-resistance effect element is a device whose resistance changes depending on the magnitude of an external magnetic field. A magneto-resistance effect type magnetic head comprising the magneto-resistance effect element as a magneto-sensitive element reproduces magnetic signals from a magnetic recording medium by detecting the changes of the resistance of the magneto-resistance effect element normally by supplying a fixed sense current to the magneto-resistance effect element and by detecting the fluctuation of voltage of the sense current.
Such a magneto-resistance effect type magnetic head produces a large reproducing output and is suited for high-density recording. Then, the magneto-resistance effect type magnetic head has come to be used widely in a hard disk unit having a high recording density. The magneto-resistance effect type magnetic head reproduces signals while floating minutely on the hard disk rotating at high speed in the hard disk unit.
Because the magneto-resistance effect type magnetic head produces the large reproduced output and is suited for the high-density recording, it is desired to be applied to a magnetic signal reproducing apparatus using a magnetic tape as a recording medium. However, the abrasion of a magnetic tape sliding face of the magneto-resistance effect type magnetic head poses a problem when the magneto-resistance effect type magnetic head is applied to the magnetic signal reproducing apparatus using the magnetic tape.
The hard disk unit causes almost no problem of abrasion because the magneto-resistance effect type magnetic head reproduces the signals while floating minutely on the hard disk rotating at high speed. However, when the magnetic tape is used as the recording medium, such problem occurs that the magnetic tape sliding face is abraded because the magneto-resistance effect type magnetic head reproduces the signals while contacting with and sliding along the magnetic tape.
The magneto-resistance effect type magnetic head reproduces the magnetic signals by supplying the fixed sense current to the magneto-resistance effect element and by detecting the fluctuation of the voltage as described above. However, when the part of the magneto-resistance effect element is abraded by sliding the magneto-resistance effect type magnetic head along the magnetic tape, the level of fluctuation of the voltage of the sense current corresponding to the signaling magnetic field from the magnetic tape changes. As a result, the reproduced output obtained from the magneto-resistance effect type magnetic head fluctuates considerably and the signals cannot be reproduced normally.
The magnetic tape sliding face of the magnetic head is very liable to be abraded because the magnetic tape slides along the magnetic head at high speed in the helical scan type magnetic signal reproducing apparatus in particular. Therefore, it has been very difficult to apply the magneto-resistance effect type magnetic head to the helical scan type magnetic signal reproducing apparatus.